1. Field of the Invention
The invention relates to a flash memory and a manufacturing method and an operating method thereof, and more particularly, to a flash memory capable of avoiding a second bit effect and enhancing performance of devices, and a manufacturing method and an operating method thereof.
2. Description of Related Art
The non-volatile memory is characterized by maintaining the data stored even when the power is down, and has thus become a mandatory device in many electronic products for providing normal operation of the electronic products when booted. In particular, flash memory allows multiple data writing, reading, and erasing operations. With these advantages, flash memory has become one of the most widely adopted memory devices in personal computers and electronic equipments.
Currently, a popular flash memory such as a nitride-based flash memory. In the nitride-based flash memory, two-bit data can be stored in a charge-trapping structure with a constitution of oxide layer-nitride layer-oxide layer (that is, the conventional ONO layer). In general, two-bit data can be stored respectively on the left side (i.e. the left bit) and the right side (i.e. the right bit) of the nitride layer in the charge-trapping structure.
Nevertheless, the nitride-based flash memory has a second bit effect; that is, a reading operation performing on the left bit is affected by the right bit, or a reading operation performing on the right bit is affected by the left bit. In addition, the second bit effect becomes worsen with the gradual reduction in the sizes of memories, thereby affecting the operation window of the memories and the performance of the devices.